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Liang J.,State Oceanic Administration | Liang J.,Sun Yat Sen University | Liang J.,Guangdong Provincial Key Laboratory of Geological Processes and Mineral Resources Survey | Zhou Y.,Sun Yat Sen University | And 3 more authors.
Earth Science Frontiers | Year: 2015

South China was formed by amalgamation of the Yangtze and Cathaysia blocks, both of which have basement built from the Archean to the Mesoproterozoic. Based on the Proterozoic oceanic crust, evidenced by ophiolite and mafic-ultramafic rocks, it was believed that the final amalgamation happened during the Neoproterozoic. The formation of the juncture, called Qinzhou-Hangzhou suture zone (QHSZ), and intracontinental magmatism afterwards have relevance to the assemblage and break-up of supercontinent. The geological evolution of the suture zone is described as “twice opening, triple closure and once turning”. The QHSZ is an important porphyry copper deposit (PCD) belt. The PCDs are well distributed in the north, the middle and the south segment of the suture zone. They are mainly formed in the Yanshanian period, by two eras of 170-150 Ma and 100 Ma or so. The associated porphyries are mainly granodiorite porphyry, granite porphyry and monzonitic granite-porphyry, which belong to the calc-alkaline magma series of acidic rock. Geodynamic of Mesozoic porphyry petrogenesis and mineralization in QHSZ was closely relative to the subduction of Paleo-Pacific plate; materials for ore formation might have been derived from remobilizing of arc magma by ancient subduction. Triggered by dynamic mechanism of lithospheric thinning and subduction of Paleo-Pacific Plate, the upwelling of asthenospheric mantle brought massive heat, heating the overlying Proterozoic arc basaltic rocks and led to the formation of ore magma. It is concluded that such acidic porphyries of the QHSZ resulted from the partial melting of the Proterozoic island arc basaltic rocks triggered by the subduction, including the direction changing of the Paleo-Pacific Plate during the Mesozoic period, and that the associated PCDs have the gene of island arc subduction environment. ©, 2015, Chinese Academy of Forestry. All right reserved. Source


Zeng C.,Guangxi Geological Survey Institute | Zeng C.,Guangdong Provincial Key Laboratory of Geological Processes and Mineral Resources Survey | Zhou Y.,Sun Yat Sen University | Zhou Y.,Guangdong Provincial Key Laboratory of Geological Processes and Mineral Resources Survey | And 8 more authors.
Earth Science Frontiers | Year: 2015

The Qinzhou Bay (Q)-Hangzhou Bay (H) juncture orogenic belt is a giant suture separating Yangtze Block from Cathaysia Block in South China. Before involving into the Western Pacific active continental margin, it underwent several stages of regional-scale tectono-magmatism events. Assembly-collision had taken place between Yangtze Block and Cathaysia Block during the Neoproterozoic Sibao orogeny (1000-880 Ma), with suture spreading from the Jiangshan-Shaoxing Fault, through northeastern Jiangxi Province and eastern Hunan Province, to the Qinzhou Bay of Guangxi Province. Post-collision process included post-orogeny magmatism stage and extension-break up stage, with broad extensional basin between Yangtze and Cathaysia Blocks. During the Silurian (460-410 Ma) and the Indosinian (250-200 Ma), Yangtze Block and Cathaysia Block re-assembled, leading to the regional-scale tectono-magmatism and the united depositional environment in South China. Affected by the West Pacific subduction, the transformation of tectonic regime during the Late Jurassic (125-140 Ma) in South China turned the tectonic setting from compression to lithosphere thinning, arousing intensive magmatism and mineralization. Three segments, the northern, the middle and the southern, may be distinguished by the geological variation and are divided roughly at latitudes 24° and 27° north. The middle section is overlapped with the traditional Nanling Belt; the northern section is roughly coincident with the Shaoxing-Jiangshan-Pingxiang zone; and the southern section with the Yunkai-Shiwandashan Mountainous zone. Chronological and chemical studies show that meta-mafic and ultramafic rocks found in the western Yunkai massif were formed in the Neoproterozoic and display MORB or ITA characteristics. The Caledonian meta-volcanic rocks in the Cenxi area display the same MORB chemical characteristics. The Early Mesozoic felsic volcanics and rhyolite in the both sides of Shiwandashan Mountains also display geochemical characteristics of typical subduction-related arc volcanic rocks. Therefore, a paleo ocean plate did exist in the Q-H juncture orogenic belt, the same as the evolution of north segment, which underwent collision and orogeny events during the Neoproterozoic, Caledonian and Indosinian eras. ©, 2015, Chinese Academy of Forestry. All right reserved. Source


Liang J.,State Oceanic Administration | Liang J.,Sun Yat Sen University | Liang J.,Guangdong Provincial Key Laboratory of Geological Processes and Mineral Resources Survey | Zhou Y.,Sun Yat Sen University | And 7 more authors.
Earth Science Frontiers | Year: 2015

The Nanhe area is located in Lianjiang County, Guangdong Province, southern section of Qinzhou Bay-Hangzhou Bay metallogenic belt (QHMB), which has recorded the geological evolution of the south section of QHMB. According to the statistics of sedimentary strata, the hydrodynamic environment of stratigraphic forming in the study area were mainly littoral, shallow marine, deep-sea phase, and minor fluvial facies and swamp facies. Obviously, there was multi-stage of magmatic activity in the research area, which could be divided into two large cycles of Caledonian and Mesozoic. Based on the lithological change, regional metamorphism law could be summarized as that the participation of magma migration decreased due to distance increasing. Thus, the farther the metamorphism from the intrusive mass, the lesser relationship with the magma, resulting in the formation of a sequence with the metamorphic grade gradually reduced, i.e., migmatite→schist→ phyllite → metamorphic sandstone. ©, 2015, Chinese Academy of Forestry. All right reserved. Source


Lao M.,Sun Yat Sen University | Lao M.,Guangdong Provincial Key Laboratory of Geological Processes and Mineral Resources Survey | Zou H.,Sun Yat Sen University | Zou H.,Guangdong Provincial Key Laboratory of Geological Processes and Mineral Resources Survey | And 4 more authors.
Earth Science Frontiers | Year: 2015

The Mashan igneous complex, occurring in the southwestern segment of the Qinzhou-Hangzhou metallogenic belt with outcropping in the west side of the Fangcheng-Lingshan fault zone, is composed of alkali shoshonitic rocks in which basic, mediosilicic and acid rocks are included. Geochronology and geochemistry of the mediosilicic intrusive rocks have been studied in detail in this paper. A sample of the rocks have a 40Ar/39Ar plateau age of 153.8±0.6 Ma, indicating that the rocks were formed in the Late Jurassic. Samples of the rocks are all abundant in alkaline elements of K and Na, with K2O+Na2O being of 5.73%-8.54%, K2O/Na2O=0.87-1.76. They are enriched in the large-ion lithosphile elements of Rb, Ba, Th, U and LREE, and their isotopic compositions are characterized by that the ratios of (87Sr/86Sr)i range from 0.70511 to 0.70547, εNd(t) from 0.6 to 1.4,206Pb/204Pb=19.019-19.228, 207Pb/204Pb=15.720-15.737, and 208Pb/204Pb=39.372-39.518. These geochemical data show that the magma was derived from the sources mixed by two end-members of the DMM asthenosphere and the EM II lithosphere. It suggests that upwelling of the asthenosphere and extension of the lithosphere probably took place in southeast Guangxi during the Late Jurassic, which possibly were the tectonic settings of formation for the Yanshanian granites and the related mineral deposits in the southwestern segment of the Qinzhou-Hangzhou metallogenic belt. ©, 2015, Chinese Academy of Forestry. All right reserved. Source


Li H.,Guangdong Highway Design Institute Co. | Li H.,CAS Institute of Geology and Geophysics | Li H.,Guangdong Provincial Key Laboratory of Geological Processes and Mineral Resources Survey | Zhou Y.,Guangdong Provincial Key Laboratory of Geological Processes and Mineral Resources Survey | And 13 more authors.
Earth Science Frontiers | Year: 2015

The Qinzhou (Bay)-Hangzhou (Bay) Joint Belt (QHJB), located in the Southeast of China, runs across the Zhejiang, Jiangxi, Hunan, Guangdong and Guangxi Provinces, and is divided into north, middle and south segments with the demarcation of the Nanling tectonic zone. The middle segment of the QHJB is located primarily in the Nanling tectonic zone, which lies between latitudes 24° and 27° north approximately. Separated by the middle segment, the other two segments are north segment including provinces of Jiangxi and Zhejiang and Northern Anhui province and south segment including west Guangdong and Southeast Guangxi provinces. The siliceous rocks are widely distributed in the QHJB, especially on the both sides of the QHJB, whose geological and geochemical characteristics denote the hydrothermal genesis. The hydrothermal siliceous rocks were earlier distributed on a large scale next to the northern segment and then developed in the middle and then in the south. This phenomenon is in accordance with the distinct tectonic evolution in the three segments. It can be accounted for by a large scale hydrothermal activity in the south segment during the Neopaleozoic, and a large scale hydrothermal activity in the middle and north segments during the Eopaleozoic and the Proterozoic, respectively. The siliceous rocks represent the old hydrothermal activities and were distributed closely to the tectonic evolution and dynamics background during the tensional phases. In the QHJB, there is a wide distribution of SEDEX type sulfide deposits and hydrothermal sedimentary gold ore deposits, which indicates the abundant metallogenesis during the hydrothermal activities. ©, 2015, Chinese Academy of Forestry. All right reserved. Source

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